The present invention is directed to a crankshaft assembly, such as used in small gasoline motors for driving lawn mowers, chain saws, two-wheel vehicles, motor-driven hand tools and the like, where the crankshaft is assembled from at least one shaft pin, at least one crankshaft web, and at least one crank bolt with these parts being fabricated as separate members and subsequently assembled together as an integral unit. Such crankshafts for small gasoline motors are usually mass-produced parts, manufactured in large numbers.
It has been known to fabricate the parts making up a crankshaft as separate members and then to join them together, such as by a press or shrink fit. It is also known to weld the parts of a crankshaft after they have been interconnected in a shrinking operation. Further, in the formation of crankshafts, the crankshaft webs have been formed from a softer material than the shaft pin and crankpin, and serrations have been formed in the pins so that during assembly the pins are pressed into the softer material of the web for obtaining a closely interfitting connection between highly stressed parts. Rather than using serrated surfaces, extruded connections between the crank web and the pins are known with the pins being pressed into a web opening of smaller diameter containing grooves extending in the axial direction of the opening. Moreover, it is known in the art to interlock the individual parts of the crankshaft assembly with each other by means of pins or wedges.
In these various known crankshaft assemblies, the separately fabricated parts, based on their shape, are either cast or produced on lathes and the crankshaft assemblies made up of multiple parts are preferably used in machines with large volume displacements. Such a crankshaft construction has been provided where the crankshaft and the connecting rod have been supported in roller bearings. It was the purpose of these crankshaft assembly arrangements to simplify handling during the fabrication of the individual parts and also during the assembly operation.